The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Engine water pumps are typically belt-driven centrifugal pumps that circulate coolant through an engine to cool the engine. Coolant is received through an inlet located near the center of a pump, and an impeller in the pump forces the coolant to the outside of the pump. Coolant is received from a radiator, and coolant exiting the pump flows through an engine block and a cylinder head before returning to the radiator.
In a conventional water pump, the impeller is always engaged with a belt-driven pulley. Thus, the pump circulates coolant through the engine whenever the engine is running. In contrast, a switchable water pump includes a clutch that engages and disengages the impeller to switch the pump on and off, respectively. The pump may be switched off to reduce the time required to warm the engine at startup and/or to improve fuel economy, and the pump may be switched on to cool the engine. However, the pump may not switch on or off as commanded due to, for example, a stuck clutch.